Answer:
118 N
Explanation:
Given mass of the block, m = 4.00kg.
The acceleration of the elevator, a = 3.0 m/s^2.
As elevotar attaced with spring scale and accelerating upward
(block and elevator), so total force
[tex]F_N-mg=ma[/tex]
Here, mg is the weight of the block downward direction.
or
[tex]F_N=ma+mg=m(g+a)[/tex]
substitute the given value, we get
[tex]F_N=4kg(9.8m/s^2+3m/s^2)[/tex]
   = 117.6 N = 118 N.
Thus, the reading on the spring scale to 3 significant figures is 118 N.